Query in java classes

[Aaliya Seth]

Hello,
I am currently developing a small application that downloads images from a site. To begin, I coded everything in the main class using functions. I just tested by separating the class into several classes, but I wonder if I am doing well. I have the main class with the main function, a class tools with different functions and a class for personal exemptions. The program works as before but with more classes, but there is no inheritance between them. I use them as I did before with includes in C.

class Bug extends Exception{...}
class Tools{...}
class ImageDownloader extends Tools{....} / / main class

i think I have not understood the concept of classes properly, so if you guys can help me then it would be great. Thanks in advance.

[Linux-Us]

Hi,
If your class is Tools Utility, you can put the methods in static and so in ImagesDownloader you use something like:

... Tools.doAction(...);

Alternatively, your class ImagesDownloader could be an instance of class Tools so you can remove the extends. Without seeing the code of your classes, I can not advise you more If all your methods in Tools are independent of each other, then I would take the first option. Hope this is going to help you.

[Gunner 1]

Hello,
I am a new bee in java and even I would like to understand the concept of java. Here is what I have tried till now

Public static void crtfold(String fldnm){
		try{
			File f = new File(fldnm);
			if (!(f.exists())){
				if (!(f.mkdir()))
					throw new Bug("Can not create the new folder!");
			}
 
			/ / Change current folder
			System.setProperty("user.dir"F.getAbsolutePath());
		}
		catch(Exception e){
			System.err.System.out.println("Error in urlToFile"+ e.getMessage());
		}
	}
}

[Aaliya Seth]

Hello,
This is my updated code, if see in problem in the code then please correct me with the same
Here is the code:

Public class ImgDown extends Tools{
	Public static void hand(String args[]){
		try{
			/ / Reads the url from the keyboard 
			System.out.System.out.println("Enter an url:);
InputStream in = new InputStream(System.in);
BufferedReader BufferedReader = new BufferedReader(in);
String str = BufferedReader.readLine();
URL url = new URL(str);  / / convert string into URL format
			
			/ / Create a new folder
			createFolder(url.getHost());
		}
		catch(Exception e){
			System.err.System.out.println("Error in hand"+ e.getMessage());
		}
	}
}

[SoftWore]

Hello,
For ImagesDownloader your class does not need to expand Tools. You can do the following.

Tools.createFolder("XXFolder");

In ImagesDownloader since your method is in Tools static. Then, for the javadoc in Eclipse, you can generate it on an entire project. (Project> Generate Javadoc ... and you follow the wizard). Hope this information will help you.

[InterNetWorKed]

Hello,
I would like to mention two points here.

- When you program in Java, gradually tries to "think object" at the start, not thinking "functions". Before thinking about the functionality of your program and cut it well (as is done in C), think rather what are the actors, the entities in my system, what would characterize them, what they are able to do so.

- One of the greatest strengths of Java is its exception that mean that when used well debugging is much much much easier (and others) through the stack. From the outset, said although an exception is an object, not a single string (the message). It's a shame to lose the information from the stack. In addition, the try / catch not needed especially with catch Exception that is not really recommended to use only knowingly.